Integral label-free biosensor and analysis method using the same

Abstract

Disclosed is an integral label-free biosensor capable of analyzing a biomolecule with high sensitivity by integrating a light source, a photodetector, an optical waveguide, and a microcantilever on a substrate, and a method of detecting a bio-antigen by using the same. The integral label-free biosensor according to the present invention may be manufactured with low cost, be easily integrated with a silicon electron device, and detect a biomolecule with high sensitivity by using a label-free method.

What is claimed is: 
     
       1. An integral label-free biosensor, comprising:
 a substrate; 
 a light source disposed on the substrate; 
 a photodetector disposed on the substrate and spaced apart from the light source; 
 a first optical waveguide connected with the light source, the first optical waveguide extending toward the photodetector; 
 a second optical waveguide connected with the photodetector, the second optical waveguide extending toward the light source; 
 an insulating layer disposed between the light source and the substrate, and between the photodetector and the substrate, the insulating layer supporting the first and second optical waveguides; 
 a microcantilever connected to the first optical waveguide, the microcantilever extending toward the second optical waveguide and being configured to move with respect to the second optical waveguide; 
 a bio antibody fixed on the microcantilever; and 
 a microfluidic channel configured to provide a sample onto the microcantilever. 
 
     
     
       2. The integral label-free biosensor of  claim 1 , further comprising:
 a polymer layer disposed on the first optical waveguide, the microcantilever, and the second optical waveguide. 
 
     
     
       3. The integral label-free biosensor of  claim 2 , wherein a bio-antibody is fixed onto the polymer layer. 
     
     
       4. The integral label-free biosensor of  claim 1 , wherein the first optical waveguide and the microcantilever are integrally connected. 
     
     
       5. The integral label-free biosensor of  claim 1 , wherein the microfluidic channel is positioned over the microcantilever, the first optical waveguide, and the second optical waveguide. 
     
     
       6. The integral label-free biosensor of  claim 1 , wherein the light source includes a hole injection layer, a light emission layer, and an electron injection layer, which are sequentially stacked. 
     
     
       7. The integral label-free biosensor of  claim 6 , wherein the light emission layer comprises silicon nitride including a silicon nano crystal,
 wherein the hole injection layer includes a material selected from the group consisting of a p-type silicon thin film, a p-type silicon carbide-based thin film, and a silicon carbon nitride-based thin film, and 
 wherein the electron injection layer includes a material selected from an n-type silicon carbide-based thin film and a silicon carbon nitride-based thin film. 
 
     
     
       8. The integral label-free biosensor of  claim 1 , wherein the photodetector includes a hole doping layer, a light separation layer, and an electron doping layer, which are sequentially stacked. 
     
     
       9. The integral label-free biosensor of  claim 8 , wherein the light separation layer comprises silicon nitride including a silicon nano crystal,
 wherein the hole doping layer includes a material selected from the group consisting of a p-type silicon thin film, a p-type silicon carbide-based thin film, and a silicon carbon nitride-based thin film, and 
 wherein the electron doping layer includes a material selected from an n-type silicon carbide-based thin film and a silicon carbon nitride-based thin film. 
 
     
     
       10. The integral label-free biosensor of  claim 1 , wherein the insulating layer is a silicon oxide (SiO 2 ) thin film. 
     
     
       11. The integral label-free biosensor of  claim 1 , wherein the optical waveguide is a silicon nitride (SiN x ) thin film. 
     
     
       12. A method of detecting a bio-antigen by using the integral label-free biosensor of  claim 1 , the method comprising:
 fixing a bio-antibody onto a microcantilever connected with a first optical waveguide and disconnected from a second optical waveguide; 
 measuring a photocurrent based on light incident onto a photodetector, the light being generated by a light source and passing through the first optical waveguide, the microcantilever, and the second optical waveguide; 
 injecting a sample through a microfluidic channel, where when the sample includes a bio-antigen, the bio-antibody and the bio-antigen react on the microcantilever and a weight of the reacted bio-antibody and bio-antigen move the microcantilever toward the second optical waveguide; and 
 measuring a change in the photocurrent after the sample has been injected through the microfluidic channel. 
 
     
     
       13. The integral label-free biosensor of  claim 1 , wherein the microcantilever is spaced apart from the second optical waveguide by a first distance when the bio-antibody is unattached to a bio-antigen, and
 wherein the microcantilever is spaced apart from the second optical waveguide by a second distance when the bio-antibody is attached to the bio-antigen, the second distance being shorter than the first distance. 
 
     
     
       14. The integral label-free biosensor of  claim 1 , wherein the photodetector detects light transmitted from the light source and through the first optical waveguide, the microcantilever, and the second optical waveguide. 
     
     
       15. An apparatus, comprising:
 a light source emitting light; 
 a first optical waveguide optically coupled to the light source and configured to transmit the light emitted from the light source; 
 a microcantilever configured to transmit the light from the first optical waveguide, the microcantilever being fixed to the first optical waveguide; 
 a second optical waveguide configured to transmit the light from the microcantilever, the microcantilever being disconnected from the second optical waveguide; 
 an antibody attached to the microcantilever, the microcantilever moving toward the second optical waveguide when the antibody reacts with an antigen; and 
 a photodetector optically coupled to the second optical waveguide, the photodetector receiving the light transmitted through the second optical waveguide. 
 
     
     
       16. The apparatus of  claim 15 , wherein the microcantilever is spaced apart from the second optical waveguide by a first distance when the antibody is unattached to the antigen, and
 wherein the microcantilever is spaced apart from the second optical waveguide by a second distance when the antibody is attached to the antigen, the second distance being shorter than the first distance. 
 
     
     
       17. The apparatus of  claim 15 , further comprising:
 a microfluidic channel positioned over the microcantilever, the first optical waveguide, and the second optical waveguide. 
 
     
     
       18. The apparatus of  claim 15 , wherein the light source includes a hole injection layer, a light emission layer, and an electron injection layer, which are sequentially stacked. 
     
     
       19. The apparatus of  claim 18 , wherein the light emission layer comprises silicon nitride including a silicon nano crystal,
 wherein the hole injection layer includes a material selected from the group consisting of a p-type silicon thin film, a p-type silicon carbide-based thin film, and a silicon carbon nitride-based thin film, and 
 wherein the electron injection layer includes a material selected from an n-type silicon carbide-based thin film and a silicon carbon nitride-based thin film. 
 
     
     
       20. The apparatus of  claim 15 , wherein the photodetector includes a hole doping layer, a light separation layer, and an electron doping layer, which are sequentially stacked.